List available apps

## List apps available for a payment request Returns the paginated list of the store's apps (sale terminals) that are **not yet associated with any payment request** — i.e. the apps you can still pick when creating or updating a payment link or invoice. ### Authentication - Send the merchant API key in **`x-api-key`** (alias `x-account-api-key`). - Requires **`Merchant.payment_link.read`**. - Optionally scope the key with **`x-application-account-id`** (alias `x-account-id`). ### Query params (`PaginationDto`) - `page` (default 1) and `per_page` (default 10). ### Response Paginated envelope (`meta` + `records` + legacy `_metadata`) where each record is a formatted app. There is **no request body**. --- **Notas:** Handler: paymentRequestAppsService.getAvailableApps. Filter is StoreDataId = caller's store AND PaymentRequest is null. Accepts the deprecated alias GET /v1/payment-links/available-apps. Records are shaped by appFormatterService.transformAppForResponse.